“We wish him well and look forward to his recovery. He has made an immense contribution to making SABMiller what it is today.”

The brewing giant, whose brands include Peroni, Grolsch and Miller Genuine Draft, also released a message from the Mr Mackay to the company’s employees.

“I am inexpressibly proud of this company, what it has achieved and the shape it is in,” the message read.

“The group is in excellent hands, and Alan will now simply pick up the remaining executive responsibilities a little sooner than expected. I obviously have an additional personal objective, and that is to get well as quickly as possible for the sake of my wife and children. Thank you all for your support.”

Mr Mackay, a South African, joined SAB in 1978 and held a number of senior positions before becoming chief executive in 1999. In 2002 he led the acquisition of America’s second biggest brewer, Miller Brewing Company, to form SABMiller.